Clip forming machine and method



Nov. 10, 1959 L. HARPER CLIP FORMING MACHINE AND METHOD 3 Sheets-Sheet 1 Filed June 28, 1956 IN VEN TOR. LAFFIE HARPER Tlil @ 44, WMZWVM/ ATTORNEYS Nov. 10, 1959 HARPER 2,912,038

cup FORMING MACHINE AND METHOD Filed June 28, 1956 s Sheets-Sheet 2 4 A. IN VEN TOR.

LAFFIE HARPER ii A 7| 74 Nov. 10, 1959 L. HARPER cm? FORMING MACHINE AND METHOD 3 Sheets-Sheet 3 Filed June 28, 1956 INVENTOR. LAFFIE HARPER United States PatntOflice 2,912,038 Patented Nov. 10, 1959 CLIP FORMING MACHINE AND METHOD Laffie Harper, San Bruno, Calif.

Application June 28, 1956, Serial No. 594,660

4 Claims. (Cl. 153-28) This invention relates to a machine for forming government clips and to the method of forming said clips.

The designation government clips has been given to the clips that are employed for securing the adjacent ends of sections of square or polysided conduits together, one of which sections has an outwardly projecting flange at the end of each side and the other of which telescopically extends into the flanged end of the first mentioned section. Such clips are strips of sheet metal that are bent to form an open sided channel with the opposed sides at substantially right angles to the bottom. One side of the channel is a double layer of the strip in which one layer is an inner layer forming one of the inner sides of the channel and the other layer is integral with said inner layer along the open side of the channel and forms the outer layer. Marginal portion of the outer layer extends past the level of the bottom of the channel and this marginal portion is slightly bent in direction toward said bottomrelative to the remainder of the outer layer.

There is nothing novel about the clip, but heretofore the machines used for making these clips from flat blanks of sheet metal have resulted in errors in that the blanks have been under or over bent or else the cost of the machines for making the clips has been prohibitive due to their complexity in structure.

One of the objects of the present invention is the provision of a rugged, simple, economically made machine that is adapted to rapidly make absolutely uniform longitudinally straight clips of the above character. I

Another object of the invention is an improved method of making government clips and the like that enables the rapid making of uniform clips at less cost than heretofore. Other objects and advantages will appear in the descrip-' tion and in the drawings.

In the drawings,

Fig. l is a top plan view of the machine;

Fig. 2 is a side elevational view of the machine of Fig. 1;

Fig. 3 is an enlarged fragmentary sectional view taken along line 3-3 of Fig. 1;

Fig. 4 is an enlarged sectional view taken along line 44 of Fig. 1;

Fig. 5 is an 55 of Fig. 1;

Fig. 6 is an 66 of Fig. 1;

Fig. 7 is an enlarged sectional view taken along line 77 of Fig. l

enlarged sectional view taken along line Fig. 8 is an enlarged sectional view taken along line the same as the end illustrated; and,

enlarged sectional view taken along line enlarged sectional view taken along line Fig. 12 is a fragmentary sectional view showing the government clip in position at one side of a conduit.

In detail, the clip forming machine comprises a frame, generally designated 1, that is provided with horizontally extending spaced side frame members 2 that may be connected by a horizontal web 3 and cross bars 4 (Fig. 4) or any other suitable cross frame members. Legs 5 are adapted to support the side frame members spaced above the floor.

. Asseen in Fig. 1, six pairs of rollers are provided with the rollers in each pair positioned one above the other, and these pairs of rollers will be referred to as sets 10, 1'1, 12, 13, .14 and 15 in succession from right to left as seen in Fig. 1, the numerals appearing below the drawing for clarity since the rollers at each position are different.

The sets of rollers above mentioned are in a generally horizontally extending row, but they are not all in horizontal alignment at the adjacent strip engaging sides of the pairs, as will later be described more in detail. The blanks to be bent are delivered to the first set 10 of rollers over the table or supporting platform 17. This platform is carried by the frame 1.

. threadedly secured in the side frame members 2. The

springs react between the heads of bolts 25 and the lips 26. A cross bar 27 extends between blocks 22, 23 and is secured at its ends to said blocks. The lower roller 19 of set 10 is journalled at its ends for rotation in side frame members 2, and a pinion 28 on shaft 20 has its teeth in mesh with a gear 29 on shaft 21. g

The upper roller 18 and lower roller 19 are formed with corresponding engaging cylindrical portions at 30, 31 respectively and adjoining the side boundaries of said cylindrical portions are complementarily formed annular outwardly opening grooves 32 in roller 18 and ridges 33 on roller 19, the latter being received in the grooves on roller 18. These ridges are at the sides of roller 19, but adjoining one of the recesses or grooves 32 in roller 18 and coaxial with the roller 19, the former is provided with an annular flange 34 that extends divergently outwardly from said groove 32. This flange virtually is of frustoconical shape with the smaller diameter end at the groove. Fig. 11 is illustrative of one end of a flat blank 35 of sheet metal from which a government clip is to be formed, which blank has parallel edges 36, 37. An end portion 38 planar with the blank projects therefrom at each of the opposite ends, and the blank is to be bent along spaced parallel lines 39, 40, 41 so that the portion 42 between edge 36 and fold line 39 will form one side of a channel perpendicular to the adjoining portion 43 that is between lines 39, 40 and which portion 43 will be the bottom of the channel opposite to its open side. The portion 44 that adjoins bottom 43 and that lies between the lines 40, 41 will be bent to a position at right angles to the portion 43 and to opposed relation to portion 42 so that it will form the side of the channel opposite to side 42. The portion 45 that is between the line of bend 41 and edge 37 is wider than the portion 42, and will be doubled back on the portion 44 so that the marginal 19 the sides 47 of the table 17 so position the blank that edges 36, 37 are substantially against said sides and the blank will be fed to the rollers for bending of the portions 42, 44 downwardly as the blank is crimped in the complementarily formed groovesand ridges on said rollers (Fig. 3). This ridging and bending of the blank along lines 39, 40 as provided for by rollers 18, 19 and as seen in Fig. 3 is necessary to the further downward bending of the portions 42, 44 and to the formation of a substantially square corner at the junctures between the side walls 42, 44 of the channel and bottom 43 thereof.

In the machine shown, the distance between the centers of each of the sets of rollers 10 to 15 inclusive is approximately five and one-half inches, leaving a substantial space between each of the sets.

As the blank '35'leaves the set of rollers 10' in movement from right to left as seen in Fig. 1, it is given the bend shown in Fig. 3 and the blank then moves over a pair of horizontally extending parallel strips 48, 49 that have their flat sides vertical. These strips are secured to and against opposite sides of the upper ends of vertically downwardly extending supports 50 that, in turn, are rigidly secured at their lower ends to 'cross frame members '4 (Fig. '4). Thus the supports 50 not only function to support the strips 48, 49 in positions for supporting the blank 35 at substantially the lines 39, '40, but they also space the strips.

After leaving 'set 10 of the rollers, the blank is guided to between the upper and lower rollers 51, 52 of set 11. The upper roller 51 (Fig. 4) of set 11 is formed with an ungroov'ed cylindrical portion 53 that is of substantially the width of roller "18 between the axially outermost sides of the grooves 32 and it is provided with a conical flange 54 similar-to flange 34 onroller '18 except that 'the surfaces the flange that engage the blank 'are more steeply inclined than the "correspondingly positioned surfaces on roller 18. Also the width of the fiangeis substantially equal to the width of the portion '44 of the blank.

Before the blank 35 reaches the rollers of set 11, and approximately at the moment the leading end leaves the rollers of set 10, the upper side of the bent portion 42 of said blank is engaged by one end portion of a horizontally elongated stationary-forming mandrel 55 and the lower side of the portion 45 is also engaged by one end portion of a horizontally elongated stationary forming mandrel '56. These mandrels "55, '56 may be round, square or .polysided in cross sectional contour, and each is .securely but adjustably held on the frame by means of supporting rods 57, 58 (Fig 4) that are welded at their upperends to the mandrels, and that are threaded at their lower ends to extend through slots 59in the cross bars 4. Nuts 60, 61 above and below the cross bars :may be tightened to rigidly hold the-mandrels in position. These threaded-lower ends of the supporting rods enable vertical adjusment of the mandrels and the slots 59 :enable horizontal adjustment. Obviously locknuts may beuse'cl to lock the rodsntobars 4.

The mandrel '55 extends progressively .downwardlylin direction away frorn the set -of rollers 10 to slidably engage the portion 42 f the blank-and to progressively bend said portion downwardly toward a position perpendicular -to'th'e 'bottom or-portion 43 of saidblank'as the blank isdr'iven to the left (asseen in Fig. I). By the same'token,'mandrel 56 progressively bends .portion 44 upwardly (Fig. "4) 'since'it extends progressively upwardly and toward the axially outer side of the upper rollers offthe sets 11,12, 13. As seen in 'Fig. 4 the supportingrods 57 are bent at their upper ends to clear the outeredge 36 of portion 42 as the blank is moved along.

The lower "roller 52of-set 11 has its peripheral .sur-

facemilled and is relatively narrowso that the axial distance between the oppositely outwardly facing sides of the strips 48, 49 is about equal to the widthof the upper roller 51 and roller 52 is disposed between said strips.

Rollers 51, 52 are respectively on shafts 63, 64. Shaft 63 is journalled at its ends for rotation in blocks 22, 23 and the ends of shaft 64 are journalled for rotation in side frame members 2.

A pinion 65 (Fig. 5) on shaft 63 has its teeth in mesh with a gear 66 on shaft 64 and an idler gear 67 connects gears 29 and 66, said idler gear being supported for rotation on a stub shaft 68 carried by one of the side frame members 2.

In set 12 (Fig. 6) an upper roller 70 and a lower roller 71 are provided, which rollers are the same as rollers 51, 52 of set 11 except that the angle of the sides of the conical flange 72 of roller 70 is steeper than that of flange 54 of roller 53. Shafts 73, 74 respectively carry the rollers 70, 71 to which the latter are secured. The shaft 73 is journalled at its ends for rotation in blocks 75,76 thatcorrespondto blocks 22, 23 and which blocks are on the side framemembers 2 and are supported for yieldable upward movement .against the resistance of helical springs 77 that, in turn, are held by bolts 78 extending through the springs and through openings in lips 79 'at' the ends of blocks '75, 76 and into the frame members 2.

Apinion 80 is secured on shaft 73, the teeth of which are in 'me's'hwith the teeth on gear81 that is secured on shaft 74. An 'idler gear 82 connects gears 81, 66 (Fig. 5).

The mandrel '55 extends progressively downwardly and to a'p'ositi'on adjacent to the side of the strips 49 that is nearest fthereto :so that portion 42 of the blank is bent to 'a position more nearly perpendicular to the bottom portion 43 of the blank as the latter moves past the rollers '70, 71 (Fig. :6)

Also the mandrelf56 extendsprogressively closer to the fiange'72 direction from the set 11 of rollers to set 12 thereof so that. the portions 44, '45 thereof will be bent closer together with the portion 44 more nearly perpendiculart'o the bottom portion 43 of the blank.

'The lower roller 71 of set 12 is milled or knurled on its'outer peripheral surface to prevent slippage on the portion '43 of the blank.

Going on to the next set 13 of rollers, these rollers are sim'ilartothe rollers of set 12, there being an upper roller 85 (Fig. 7,) and a lower roller 86. The strips 48, 49 terminate just before reaching this set of rollers and the lower roller 86 is wider than the previously described corresponding rollers in sets 11, 12 so as to substantially fit 'in the channel that is formed by the bending of the blank. The outer peripheral surfaceof the roller 86 is knurled or milled the same as is the case of the other lower rollers in the previously described sets 11, 12.

The conical flange 87 onthe upper roller 85 has its blank engaging .surface almost perpendicular to the horizontal fiattoutergperipheral.surface-of-roller 85 and as the mandrels 55, 56 come progressively nearer to theupper lateral side of..lower.roller .86 eandto the side .of the flange 87, the portions 42, 44 and 45 are forced to positions almost perpendicular to =.the portion 43.

The upper roller 85 is secured on an upper shaft-88 whileadower shaft- 189 carries-the lower rollerr86 andto which the lower roller is secured. Upper shaft 88 is journalledzat its ends forrotationin blocks 75, 76, .while the ends of shaft 89 are rotatably supported in frame members 2.

A pinion 90 (Fig. 1) secured on shaft 88 has its teeth in mesh-:with-a gear-91 secured onshaft:89,;and a pinion 92 secured on shaft 93 connects the gears :91, '81, said shaftabeing, journalled at its ends :forrotation in frame members 'ThetmarrdrelsrSS, 56.eXtend-. past the rollers .of set 13 but terminate adjacent to the rollers :of.set;14 (Fig. l).

The upper roller 94of-set14 (-Fig.;8) .is. of substantially the:same width asthe width of the .bottom portion 43 of the blank 35, and is without a.flar1ge, sinceby the time the blank reaches the set 14 of rollers the portions 44, 45 of said blank are almost together and a flange would interfere with completing the bend.

The lower roller 95 of set 14 is the same width as roller 86 and may be milled or knurled if desired, although it is not usually found to be necessary.

Upper roller 94 is secured on a shaft 96 that is rotatably carried at its ends in blocks 97, 98 that in turn correspond in structure to blocks 75, 76 and which are supported for yieldable upward movement in the same manner as blocks 75, 76.

The lower roller 95 is secured on a shaft 99 that is rotatably supported by frame members 2 for rotation. A pinion 100 on shaft 96 is in mesh with a gear 101 on shaft 99, and an idler device 102 connects gears 101 and 91, the latter being on a stub shaft similar to shaft 68.

A cross frame member 27 extends between blocks 97, 98 and is secured thereto at its ends. Vertical pivots 104 respectively secure arms 105 of a pair thereof to said cross bar with said arms extending longitudinally of the machine and to opposite sides of the cross frame member on which they are supported so that one of the ends of said arms (which may be called the rear ends, being nearer to the feed end of the machine than the other or forward ends) will extend slightly past the shaft 96 and to points at opposite sides of rollers 94, 95. Shafts 106 depend from the rear ends of said arms and on the lower end of each shaft is a horizontal roller 107 (Fig. 8) positioned to engage the laterally outwardly facing sides of the portions 42 and 45 of blank 35 for bending the said portions, including portion 44, to positions substantially at right angles to the bottom portion 43. This occurs just prior to the blank reaching the set of rollers 15.

The forward ends of arms 105 have depending lugs 109 through which a bolt 110 extends (Figs. 1, 2). An expansion helical spring 111 on said bolt slidably extends between lugs 109 yieldably urging the forward ends of the arms apart so that the rollers 107 will be yieldably urged toward each other and against the portions 42, 45 of the blank. This enables the machine to take blanks of different gauges without difiiculty, which is also the purpose of yieldably mounting the blocks that carry the upper rollers of the sets to inclusive.

The set 15 of rollers comprises an upper roller 112 secured on an upper shaft 113, said shaft being supported at its ends for rotation in blocks 97, 98. This roller has a radially outwardly extending annular flange 114 extending perpendicular to the cylindrical peripheral outer surface of the roller for extending over and against the out- -wardly facing side of the portion 42 of the blank when :said portion is at right angles to the portion 43, and said 1 cylindrical surface extends over the portion 43 and against .the same.

Also carried on the shaft 113 at the side of roller 112 -opposite to flange 114 is a disc 116 having a slanted annular surface 117 that is adapted to engage the marginal portion 46 of the part 45 of the blank 35 which marginal portion extends upwardly past the level of the bottom portion 43 of the clip. This slanted side 117 extends- -divergently and axially outwardly relative to the roller 1' 112 and functions to slightly bend said marginal portion '46 slightly toward said bottom portion 43. j 116 may be splined on shaft 113 for axial movement tthereon and is yieldably urged toward the roller 112 by :a spring 119 that is around shaft 113 and that reacts between collar 120 secured on said shaft and said disc.

The disc After the blank passes the set of rollers 15 the portions 44, 45 will spring apart slightly as seen in Fig. 10 leaving :space 121 into which one side 122 (Fig. 12) of the unt'flanged end of a length of conduit extends. :along each side of the conduit and the portion 42 of the tclip is finally bent under the flange 123 of the conduit as seen in Fig. 12. The lapping portions 44, 45 and side of 5 the conduit that is between said portions may be crimped together as generally indicated at 124.

A clip is a Secured on shaft 113 is a pinion 125, the teeth of which are in mesh with the teeth on a gear 126 on a lower shaft 127 which carries the lower roller 128 of the set 15. The width of this lower roller is the same as the width of roller 95.

An idler gear 129 connects gears 126, 101.

By the arrangement described, the rotation of the upper rollers of the sets 10 to 15 inclusive is in one direction, they being driven by a motor 131 (Fig. 2). A belt 132 connects the small diameter motor pulley 133 with a large diameter pulley 134 that is secured on a shaft 135, which shaft is rotatably supported for rotation by frame member 2. A pinion 136 secured, on shaft has its teeth in mesh with the teeth of a gear 137 that, in turn, is secured on shaft 93. This arrangement provides for a substantial reduction in speed between the motor pulley 133 and the gears that support the lower rollers of the sets of rollers 10 to 15, with a corresponding increase in power.

The rotation of gear 137 is, of course, in a direction for driving the rollers of the sets 10 to 15 for movement of the blank 35 through the machine in the same direction (right to left as seen in Fig. 1) without slippage be tween the blank and the rollers of the sets.

An important feature of the invention is the relative positions of the sets of rollers 10 to 15 and particularly 10 to 14 inclusive, with respect to a line extending longitudinally of the row. The adjacent clip engaging sides of the sets of rollers 10 to 14 are not in a straight line. For example, in a machine for making standard clips that may be of approximately 8 /2 inches in maximum length between the ends of line 39 (Fig. 11) or approximately 6 inches in length between the ends of line 41, the distance between the centers of the adjacent pairs of rollers in the lower row (or upper row) may be approximately 5% inches. The relative diameters of the upper and lower rollers and of the pinions and gears connecting them for simultaneous rotation are such that the upper and lower rollers will have the same surface speed at their clip engaging sides.

In the above arrangement, the adjacent clip engaging sides of the rollers of set 11 (second set from the right in Fig. 1) will be at a level approximately 7 of an inch offset above a straight line extending between the adjacent clip engaging sides of said rollers of set 11 and the adjacent clip engaging sides of the rollers of set 14, while the adjacent clip engaging sides of the rollers of set 12 will be only /a of an inch offset above said straight line and the rollers of set 13 will be only ,4 of an inch offset above said line while the adjacent clip engaging sides of the rollers of sets 14, 15 may be on said straight line.

In the absence of such an arrangement, the clips that are formed will be curved longitudinally instead of being straight, but by the above arrangement the clips are uniformly straight. Obviously curved strips would be of no value. The principle followed in offsetting the rollers of the sets or of offsetting their adjacent clip engaging surfaces will be followed irrespective of variations in the spacing of the sets and other dimensions given as an example.

I claim:

1. A machine for forming government clips and the like from a strip of metal, comprising: a frame, a plurality of spaced pairs of rollers having adjacent strip engaging surfaces and supported on said frame in a row, means for supporting the rollers of each pair thereof on said frame in position for engaging and gripping said strip by said strip engaging surfaces at opposite sides of said strip at points spaced between the longitudinally extending edges of the latter, means connected wtih said rollers for driving them to move said strip longitudinally of the latter in one direction, a pair of stationary, elongated strip engaging means carried by saidframerespectively at opposite sides of said row of rollers having strip engaging surfaces positioned for substantially continuous slidableengagement withthe marginal portions of a strip along its longitudinally extending edges at opposite sides of said vpoints ,when such strip is :betweenthe rollers of said pairs, said surfaces on said means having progressively and uniformly varying positions relative to the roller of said pairs to progressively bend said marginal portions to positions approximately at right angles to the portion of said strip engaged between the rollers -of said pairs as said strip -is moved in :said one direction along said means, the outer peripheral surface of one of the corresponding rollers of eaeh of said pairs having a cylindrical outersurfaceadapted to engage said strip at oneside thereof and a-frustoconical surface joining one edge of the said cylindrical contour at the smaller diameter end of said frusto-oonical surface, said frusto-conical surface being positioned to engage one of said'marginal portions of said strip between one of said means and the latter for bending the portion so adapted to be engaged thereby to a position in generally opposed relation to the marginal portion engaged by said one of said means whereby said one of said marginal portions will be doubled on itself, thesaid frusto-conical surface on each succeeding of said corresponding rollers of said row in direction of movement of said strip being progressively steeper relative to the axis of each such roller.

2. A machine for forming government clips and the like from a strip of metal comprising: a frame, a plurality of spaced pairs of rollers in a row with the rollers of each pair disposed one above the other thereby providing a row of upper rollers and a row of lower rollers, means carried by said frame supporting said rollers for rotation and means connecting said rollers for rotation of the pairs thereof for driving a generally horizontally disposed strip longitudinally thereof in one direction between said upper rollers and said lower rollers from one end pair of rollers at one end of said row and past the last end pair of rollers at the other end ofsaid row, the said rollers of said pairs being of less width than the width of such strip before bending thereof and positioned to engage an intermediate portion of said strip spaced between the longitudinal edges of said strip, means connected with the rollers of said pairs for driving them to move said strip in said one direction, a first elongated stationary forming mandrel at one side of said row positioned for slidably engaging the upper side only of one marginal portion of said strip at variable distances from the lower rollers of said row for bending said one marginal portion downwardly and substantially at right angles to the portion engaged by said rollers as said strip is moved longitudinally of said row, separate means at the other side of the rollers of said row including extensions on said rollers and a stationary elongated forming mandrel similar to said first mandrel, said extensions projecting generally radially outwardly of said rollers for engagement with one side of the other marginal portion of said strip at points adjacent to said rollers and said mandrel being in a position to engage the side of said other marginal portion that is opposite to the side engaged by extensions and along a line spaced outwardly of said extensions relative to said intermediate portion for bending the other marginal portion of said strip on itself and inopposed relation to said one marginal portion as said strip is moved in said one direction.

3. A machine for forming government clips from a strip of metal comprising: a frame, a plurality of spaced pairs of rollers in a horizontally extending row with the rollers of each pair disposed one above the other thereby providing a row of upper rollers and a row of lower rollers adapted to engage the upper and lower sides of an intermediate portion of a strip, means on said frame supporting said rollers for rotation about parallel horizontal axes. means connecting said rollers for simulta eousrotation for driving a substantially horizontally disposed strip longitudinally thereof in one direction between said upper and lower rollers from one end pair of said row to and past the last end pair of rollers at the other end of said row, successive pairs of said rollers of said row in direction from said one end pair toward said'last end pair being progressively spaced upwardly from a straight horizontal line vextending longitudinally of said rowandmidway between the rollers of said one end pair, a first, elongated, stationary mandrel at one side of said row extending generally longitudinally thereof in a position for slidably engaging the upper side only of one-marginal portion of such strip at variable distance from the lower rollers of said row for bending said one marginal portion downwardly to a position substantially at right angles to an intermediate portion of said strip adapted to be engaged by the adjacent outer peripheral sides of the rollers of each pair thereof, a second elongated mandrel similar to said first mandrel spaced outwardly of said row at the side thereof opposite to said first mandrel and positioned to engage the lower side only of the other marginal portion of said strip that is opposite to said one marginal portion, radially outwardly projecting flanges on one end only of certain of said rollers for engaging the upper side only of said other marginal portion at points between said second mandrel and said rollers for bending said other marginal portion on itself and in opposed relation to said one marginal portion, said certain of said rollers including said one end pair and a-plurality of said pairs successively spaced therefrom toward said last pair and terminating short of said last pair, a circular disc coaxial with and adjacent one side of said last pair adapted to engage the laterally facing side of said other marginal portion along one free longitudinally extending edge of said strip for bending the part of said strip engaged thereby generally toward the roller adjacent to said disk, said disk being rotatable with the roller adjacent thereto and yieldable means engaging said disk for yieldably urging it against said last mentioned roller.

4. A machine for forming government clips from a strip of metal comprising: a frame, a plurality of spaced pairs of rollers in a horizontally extending row with the rollers of each pair disposed one above the other thereby providing a row of upper rollers and row of lower rollers adapted to engage the upper and lower sides of an intermediate portion of a strip, means on said frame supporting said rollers for rotation about parallel horizontal axes, means connecting said rollers for simultaneous rotation for driving a substantially horizontally disposed strip longitudinally thereof in one direction between said upper and lower rollers from one end pair of said row to and past the last end pair of rollers at the other end of said row, successive pairs of said rollers of said row in direction from said one end pair toward said last end pair being progressively spaced upwardly from a straight horizontal line extending longitudinally of said row and midway between the rollers of said one end pair, a first, elongated, stationary mandrel at one side of said row extending generally longitudinally thereof in a position for slidably engaging the upper side only of one marginal portion of such strip at variable distance from the lower rollers of said row for bending said one marginal portion downwardly to a position substantially at right angles to an intermediate portion of said strip adapted to be engaged by the adjacent outer peripheral sides of the rollers of each pair thereof, a second elongated mandrel similar to said first mandrel spaced outwardly of said row at the side thereof opposite to said first mandrel and positioned to engage the lower side only of the other marginal portion of said strip that is opposite to said one marginal portion, radially outwardly projecting flanges on one end only of certain of said rollers for engaging the upper side only of said other marginal portion at points between said second mandrel and said rollers for bending said other marginal portion on itself and in opposed relation to said one marginal portion, said certain of said rollers including said one end pair and a plurality of said pairs successively spaced therefrom toward said last pair and terminating short of said last pair, a circular disc coaxial with and adjacent one side of said last pair adapted to engage the laterally facing side of said other marginal portion along one free longitudinally extending edge of said strip for bending the part of said strip engaged thereby generally toward the roller adjacent to said disc, said disc being rotatable with the roller adjacent thereto and yieldable means engaging said disc for yieldably urging it against said last mentioned roller, a pair of vertically disposed strips at opposite sides of the pair of rollers adjacent to said last pair thereof and against the oppositely outwardly facing sides of which said marginal portions are adapted to be positioned in opposed relation thereto, and a pair of rollers supported for rotation about vertical axes positioned adjacent to said oppositely outwardly facing sides for urging said marginal portions against said last mentioned sides.

References Cited in the file of this patent UNITED STATES PATENTS 803,859 Shifley Nov. 7, 1905 901,637 McKenzie Oct. 20, 1908 1,266,545 Anderson May 21, 1918 1,574,397 Kirsch Feb. 23, 1926 1,730,361 Fulenwider Oct. 8, 1929 1,955,546 Ingels Apr. 17, 1934 2,145,526 Penkala Jan. 31, 1939 2,505,241 Gray Apr. 25, 1950 2,680,466 Ingels June 8, 1954 2,826,235 Gudmestad Mar. 11, 1958 

